Hold previous date

Shell Programming and Scripting
1

A file named abc.txt being updated with date value by one process.

Say , today it s updating the file with value

01-09-2009

Fine. Tomorrow the process will override the file with tomorrow date (02-09-2009) .Insome case the process will overriding the file with empty string.

So I want script to check whether the file has value or empty string. If some value means leave it as it is . if empty string means , the script should override the file with previous dae value (01-09-2009). and i scrit should delete if any whitspace or tab or empty newline charectedr from the file

Thanks in advance

2

Don't multi post the same question in two threads. You can continue in your old thread by providing the proper input and expected output .